Vertex Standard VX-520U, Service Manual

Page: 15 / 52

15
Alignment
PLL & Transmitter
Set up the test equipment as shown for transmitter
alignment. Adjust the supply voltage to 7.2 V for all steps
where not specified otherwise.
UHF Transceiver Required Test Equipment
H
IBM PC compatible computer
H Vertex Standard VPL-1 Cable, or FRB-2 Service Kit, with
CE37 Channel Programming Diskette
H Vertex Standard CN-1 BNC Adapter plug
H
RF Signal Generator with calibrated output level at 1 GHz
H Deviation Meter (Linear Detector)
H
AC Voltmeter
H SINAD Meter
H
In-Line wattmeter with 5% accuracy at 1 GHz
H Regulated DC Power Supply adjustable from 4 to
10 V, 3 A
H 50-
Ω
Non-reactive Dummy Load: 10 W at 1 GHz
H
Frequency Counter: ±0.2 ppm accuracy at 1 GHz
H AF Signal Generator
H
DC Voltmeter: high impedance
Before beginning alignment, connect the transceiver and
PC using the VPL-1 Cable or FRB-2 Set as described in
the EEPROM Programming chapter, and download the
EEPROM data from the transceiver to the computer.
Then store this data in a disk file so that it can be up-
loaded when alignment is finished.
You should find the corresponding data file on the com-
puter disk for the transceiver version you are aligning, con-
taining channel settings for the high edge, middle and low
edge of the transceiver’s frequency range in channels 1, 2
and 3, respectively. Up-load this file to the transceiver.
PLL & Transmitter Alignment Points (I)
HIGH BAND
EDGE CH. (3)
470.0 MHz
LOW BAND
EDGE CH. (1)
450.0 MHz
BAND CENTER
CH. (2)
460.0 MHz
L2402
L2406
VR3204
VR3201
VR3202
TC2101 C2105
PLL VCV (Varactor Control Voltage)
Ë Connect the DC voltmeter between C2105 on the PLL
Unit and chassis ground.
Ë Set the transceiver to CH 3 (high band edge), and ad-
just L2402 on the VCO Unit for 3.5 V ± 0.1 V on the
voltmeter.
Ë
Transmit on the high band edge, and adjust L2406 for
3.5 V ± 0.1 V on the voltmeter.
Ë
Set the transceiver to CH 1 (low band edge), and con-
firm the low-end VCV is more than 1.3 V while trans-
mitting, and also while receiving.
PLL Reference Frequency
Ë
With CH 2 (band center) selected, key the transmitter
and adjust TC2101 on the PLL Unit, if necessary, so the
frequency counter displays the band center frequency
±300 Hz (for the version being aligned) when transmit-
ting.
50-ohm
Dummy Load
Inline
Wattmeter
Freq. Counter
Deviation
Meter
AC Voltmeter
Sampling
Coupler
AF Signal
Generator
ANT
Regulated DC
7.2V PSU
AC Voltmeter
MIC
PLL & TX Alignment Setup